<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script type="text/javascript">
        if (true){
            console.log('true');
        }
        if (0){
            console.log('0');
        }
        if (!0){
            console.log('!0');
        }
        if (12){
            console.log('12');
        }
        if (''){
            console.log('空字符串');
        }
        if (‘abc){
            console.log('abc');
        }
        if (null){
            console.log('null');
        }
        if (!null){
            console.log('!null')
        }
    </script>

</head>
<body>

</body>
</html>